[PATCH v4 08/12] dir.c: accept a directory as part of cone-mode patterns

From: Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>
Date: May 21, 2021, 11:59 UTC
Message-ID: <2cc3a93d4434d546cf385fa2c902064748f1b2b6.1621598382.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.932.v4.git.1621598382.gitgitgadget@gmail.com>

From: Derrick Stolee <dstolee@microsoft.com>

When we have sparse directory entries in the index, we want to compare that directory against sparse-checkout patterns. Those pattern matching algorithms are built expecting a file path, not a directory path. This is especially important in the "cone mode" patterns which will match files that exist within the "parent directories" as well as the recursive directory matches.

If path_matches_pattern_list() is given a directory, we can add a fake filename ("-") to the directory and get the same results as before, assuming we are in cone mode. Since sparse index requires cone mode patterns, this is an acceptable assumption.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 dir.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/dir.c b/dir.c
index 166238e79f52..ab76ef286495 100644
--- a/dir.c
+++ b/dir.c
@@ -1378,6 +1378,17 @@ enum pattern_match_result path_matches_pattern_list(
 	strbuf_addch(&parent_pathname, '/');
 	strbuf_add(&parent_pathname, pathname, pathlen);
 
+	/*
+	 * Directory entries are matched if and only if a file
+	 * contained immediately within them is matched. For the
+	 * case of a directory entry, modify the path to create
+	 * a fake filename within this directory, allowing us to
+	 * use the file-base matching logic in an equivalent way.
+	 */
+	if (parent_pathname.len > 0 &&
+	    parent_pathname.buf[parent_pathname.len - 1] == '/')
+		strbuf_add(&parent_pathname, "-", 1);
+
 	if (hashmap_contains_path(&pl->recursive_hashmap,
 				  &parent_pathname)) {
 		result = MATCHED_RECURSIVE;

-- 
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